Typical ionic liquids are non-volatile and non-flammable. In addition, they have wide electrochemical stability window and high ionic conductivity. These properties make ionic liquids (e.g., salts with melting points below 100° C.) useful for a wide variety of applications, including as electrolytes in batteries, capacitors and solar cells. For electrochemical applications, very high purity ionic liquids are required.
Conventional methods for manufacturing ionic liquids use batch processes and utilize organic solvents that must eventually be removed in order to use ionic liquids as electrolytes. Typical methods for producing ionic liquids involve a quaternization step to produce the required cation, followed by a metathesis step to substitute the required anion. In many cases, the salt produced by the quaternization step is solid at room temperature, which complicates handling and makes it difficult to utilize a continuous process.
Because a continuous process would greatly increase the efficiency of producing ionic liquids, there is an intense interest in developing a continuous ionic liquid producing process. Moreover, if one can eliminate the use of a solvent in ionic liquid producing process, it would further enhance ionic liquid producing process and greatly reduce the overall time and cost by eliminating a need to separate and/or dispose the solvent.